Turbine oil composition method for making thereof

ABSTRACT

Provided are formulations, methods of making, and methods of using one or more isomerized base oils in a turbine oil composition to enhance thermal and oxidative stability of the oil, as well as to improve the performance of an industrial turbine housing the turbine oil composition. The isomerized base oil having consecutive numbers of carbon atoms and has less than 25 wt % naphthenic carbon by n-d-M. The turbine oil composition has a viscosity index of greater than about 150.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No.11/316,311, filed Dec. 21, 2005. This application claims priority to andbenefits from the foregoing, the disclosure of which is incorporatedherein by reference.

TECHNICAL FIELD

The present invention relates to a turbine oil composition. Morespecifically, the present invention relates to a turbine oil compositioncomprising a major amount of one or more Fischer-Tropsch derived-baseoils (FTBOs”). That composition has a viscosity index (“VI”) of greaterthan 150, improved oxidation stability, reduced varnish- andsludge-forming tendencies, improved ability to release entrained air,and reduced tendency to catch fire over corresponding turbine oilcompositions comprising the same additives but only non-FTBO.

BACKGROUND

Industrial turbines are used to convert kinetic energy into power. Themost common industrial turbines are steam turbines, gas turbines andhydraulic turbines. Though varying considerably in complexity, theirbasic designs are essentially the same across the turbine types.Accordingly, suitable turbine oils are typically not specificallyformulated for a single type of turbine, but rather are generallyformulated for multiple types. The turbine oils thus share certainfeatures, such as, for example, the basic capacity to provide reliablelubrication and performance under high operating temperatures forsustained periods of time.

Steam turbines are among the most efficient of heat engines. They aretypically used to drive machines such as electric generators,compressors and pumps, by converting the heat of steam to velocity orkinetic energy and then to mechanical energy. Aside from the majorcomponents, such as nozzles, valves, turbine blades, exhausts, andbearings, steam turbines also typically comprise a number of auxiliarysystems that insure their safe and efficient operation. One of thoseauxiliary systems is the lubricating oil system, which provides clean,cool lubricating oil to the steam turbine bearings at the correctpressure, temperature, and flow rate. Certain of the steam turbines areequipped with mechanical-hydraulic control systems wherein thelubricating oil systems also lubricate the hydraulics. The exceedinglyhigh operating temperatures and the otherwise harsh conditions in steamturbines place certain taxing demands on the oils, requiring, forexample, sufficiently unvaried viscosity throughout the operatingtemperatures; resistance to fire, oxidation, sludge/varnish formation,and foaming; and anticorrosion properties.

Gas turbines are commonly used in the electrical power industry to drivegenerators, compressors and pumps by converting part of a fuel'schemical energy into useable mechanical energy. A gas turbine, like asteam turbine, comprises major components and auxiliary systems, withthe latter comprising a lubricating oil system in addition to others. Ina small number of gas turbines the lubricant oils are insulated fromheat, but in a majority of gas turbines, bearings and other majorcomponents are exposed to high operating temperatures, and in localizedareas, these temperatures can be higher than those found in typicalsteam turbines. The capabilities of gas turbine oils to rapidly cool thesurfaces without catching fire and retaining performance under extremeheat are thus put to the test. Even in the small number of gas turbineswhere the lubricant oils are not heated, however, oxidative stressremains because turbines typically undergo long periods of operationwithout oil service. Accordingly, a suitable gas turbine oil, just likea suitable steam turbine oil, should not only provide clean and coollubrication to the components, but also be fire resistant and imperviousor nearly impervious to oxidation, rusting and/or corrosion.

Hydraulic turbines are typically found in hydroelectric power plants,wherein they convert the energy of falling water into mechanical work.In hydraulic turbines, the main parts requiring lubrication are theshaft bearings, the wicket gates, and the inlet valves. The lubricatingoil is typically not subject to high temperatures, but its capacity toseparate water from oil takes on added importance because of the everpresence of water in the operating environment. Accordingly, a suitablehydraulic turbine oil will have superior water separating capacity aswell as the capacity to maintain adequate fluidity at low temperatures.It will also have sufficient capacity to resist rust and corrosion, aswell as the capacity to settle harmful water rapidly. Because of thelarge amounts of water in the environment, a suitable hydraulic turbineoil will have minimum tendency to foam, retain air, and/or form sludge.

Therefore a suitable general-application turbine oil will have a seriesof desirable properties to accommodate various operating conditionsacross multiple types of modern industrial turbines. These propertiesinclude, for example, sufficiently high VI, adequate oxidation stability(and relatedly, long life), low varnish/sludge formation, high fireresistance, good water-separation capacity, improved rust and/orcorrosion resistance, and improved air release and foaming properties.

A turbine oil, like other types of industrial lubricant oils, typicallycomprises an additive part and a base stock part. Accordingly,satisfactory performance may be conferred by suitable choices of eitheradditives or base stocks. Many known additives have been developed andapplied by persons skilled in the lubricant art to individually conferthe desired properties listed above, including, for example, viscosityindex improvers, corrosion inhibitors, pour point depressants,antioxidants, antifoamants, detergents, and demulsifiers. In the contextof turbine oils, however, the extent to which these properties can beimproved upon by additives is often limited.

For example, VI improvers, which are typically high molecular weightpolymers, are widely used by persons skilled in the art to increase theVI of a lubricating oil. The extent to which the VI can be improved uponusing one or more VI improvers is however limited, at least in thecontext of a turbine oil. This is because large amounts of VI improverscan be prohibitively expensive. Moreover, VI improvers are known todegrade rapidly under the operating conditions of a turbine so that theservice life of a turbine oil containing a significant amount of one ormore conventional VI improvers may be detrimentally reduced.Consequently, these potential difficulties have prompted some turbinemanufacturers to prohibit the use of VI improvers in oils used tolubricate their turbines.

Moreover, various known antioxidants are often blended into lubricantoils to improve the oxidative stability and prolong the service life ofthe oil. One of the mostly commonly used antioxidants is zincdihydrocarbyl diphiophospate, a multi-functional additive that possessesnot only the antioxidation properties but also antiwear/extreme pressurefunctionalities. However, these conventional antioxidants are known tobe problematic when added to turbine oils because they have a tendencyto hydrolyze when exposed to moisture and the hydrolysis products (e.g.,zinc oxide and hydroxide) can precipitate. This problem is so severethat many turbine manufacturers place strict limits on the content ofzinc in turbine oils, prompting the use of ashless antioxidants in theirplace. One of the most widely used replacement ashless antioxidants is2,6-ditertiarybutyl-p-cresol (DBPC or BHT). But BHT is known to havehigh volatility and it is typically made in solid form, causingdifficulties in blending. Aromatic amines tend to be more effectiveantioxidants at high temperatures than high-molecular-weight hinderedphenols, but they can be costly and tend to color the base stock inwhich they are used, forming deposits if improperly formulated. Theseantioxidants are also known to be suitable and satisfactory only whenused in a limited concentration range and a limited number of basestocks. Other antioxidants, such as phosphites, are known to besensitive to moisture, resulting in the formation of corrosive acids,and are thus avoided in turbine oils. Accordingly, just like VIimprovers can only be used to enhance the performance of a turbine oilsomewhat, antioxidants can only enhance its oxidative stability andservice life to a limited extent.

To enhance the oxidative stability, metal deactivators are alsosometimes used in conjunction to or instead of antioxidants in the artto counteract the catalytic effects from contaminating iron, copper,and/or other transition metals. But as stated in, for example, EPPublication No. 0 316 610 A1, the addition of metal deactivators maydecrease the anti-seizure and antiwear properties of theantiwear/extreme pressure agents that can be used in turbine oils.Accordingly, metal deactivators are again only of limited value.

In a further example, to inhibit foam and assist the release ofentrained air, persons skilled in the lubricant art typically use one ormore antifoamants, which include silicone fluids such aspolydimethylsiloxanes. The most active antifoamants are those that arenot soluble but dispersible in the oil or fluid because solublesiloxanes do not have the same activity at the air/fluid interface. Theresulting difficulties in obtaining a homogenous dispersion can not beignored, especially when more than a minute amount of siloxanes is used.The polymers tend to accumulate at the surface and then deposit on thewalls of the tanks so that overtime the efficiency of the additive islost. It is also known that, at high concentrations, these antifoamantstend to have an adverse effect on air release properties.

Accordingly, the approach of using additives as the sole means toachieve the desired properties in a turbine oil is inherently limited.Moreover, certain desired properties such as fire resistance cannot beachieved by including additives in an oil. On the other hand, carefulselections of base stocks may provide performance improvements in areaswhere additives cannot.

Prior to the 1980's, solvent-refined hydrocarbon oils were extensivelyused for both steam and industrial gas turbine applications. In thistype of base stock, about 35 to 60% of the hydrocarbons are in the formof saturated straight- or branched-chain paraffins andmonocycloparaffins, but there still is a significant amount ofunsaturated ring structures. The refining process removes wax (mainlyhigh molecular weight paraffinic compounds), most of the aromatichydrocarbons, and some of the polar compounds containing oxygen andnitrogen, products that would otherwise significantly reduce stabilityof the oil. But small amounts of sulfur-containing compounds typicallyremain, which are known to increase the stability of the base stock.These base stocks are classified as Group I according to the APIClassification of Base Oils. An oil in this group typically has a VI ofbetween about 80 to about 120. As operating conditions of industrialturbines became more severe, attention was turned to processes that canremove yet more of the aromatic content and the residual impurities.Since the mid-1980s, oils produced by hydrotreating, hydrocracking orhydro-refining processes have resulted in the availability of much purerbase stocks, such as those falling within API Group II (mildlyhydrocracked) and/or Group III (severely hydrocracked or hydrotreated).An oil in Group II typically has a VI of about 80 to about 120, while anoil in Group III typically has a VI of above 120 but lower than about140. These highly refined oils may, however, be less oxidatively stablecompared to solvent-refined oils such as those in Group I, because ofthe removal of sulfur and aromatic compounds during the refining processthat otherwise act as naturally occurring stabilizers. The loss ofaromatics also results in reduced additive solvency. The loss of sulfurfurther reduces the anti-wear/extreme pressure properties of these oilsalthough these properties may be improved by incorporating suitableadditives. Importantly, any further refinement beyond the extent towhich a Group I oil is refined invariably increases the costs associatedwith production, thus preventing the use of Groups II and III oils inlarge volumes.

On the other hand, polyalphaolefins (PAOs) are synthetic fluids thathave many of the desired properties to be a turbine oil base stock.These oils are manufactured by the oligomerization of alpha-olefins,particularly α-decene, but also by α-octene and α-dodecene. PAOs arefree of aromatic hydrocarbons, sulfur, oxygen, and nitrogen compounds,and show excellent response to antioxidants. These oils have higher VIsthan Groups I to III base oils. PAOs also have relatively high flashpoints, typically in the range of 230-235° C., as measured by ASTMD92-05a. They are also known to have good low temperature viscosities,as measured by ASTM D445-06, having a viscosity of 7830 mm²/s at −40°C., a temperature at which other types of base oils would have longsince solidified. These oils are further known to have good pour points,and a wide operating temperature range. Despite these advantages,additives can encounter solubility problems when being dissolved intoPAOs because of the lack of aromaticity in those base oils. PAOs alsohave limited dispersency and do not penetrate rubber seals to causeswelling, making it necessary to always blend small amounts of a sealswelling agent to prevent seal leakage. Various viscosity grades of PAOsare available, but even at their lowest viscosity grades, PAOs can bedramatically more expensive than base oils of Groups I to III, and thehigh costs associated with producing PAOs is one of the most importantobstacles that has so far prevented these oils from being widely used asbase stocks for turbine oils. Indeed, in a modern industrial turbine,the sump capacity may range from 1,000 gallons to 20,000 gallons, makingit prohibitively expensive to fill even 5% of that volume, which is thetypical annual makeup rate for replenishing the degradation loss.

Thus it would be advantageous to identify other sources of non-PAO baseoils that have similar if not better performance but without theattendant high costs for use in a turbine oil. FTBOs, which have alreadyfound use in a divergent array of non-turbine industrial lubricants, maysuitably serve this purpose.

For example, a lubricating oil having a kinematic viscosity at 40° C. offrom 18 to 60 mm²/s, a VI of from 130 to 150, and a density at 15° C. offrom 0.80 to 0.84, was said to be a suitable hydraulic fluid withdemonstrated improved efficiency in a hydraulic energy transmission inpublished U.S. Patent Application 2004/0224860 A1. That lubricating oilcomposition was said to suppress the formation of sludge and haveexcellent storage stability, low friction properties, small pressuretransmission loss, low supply pressure loss in pipe-work, and lowflammability.

In another example, a wide-cut lubricant base stock prepared fromhydroisomerizing and catalytically dewaxing a waxy Fischer-Tropschsynthesized hydrocarbon fraction feed was combined with a commercialautomotive additive package, yielding a multigrade internal combustionengine crankcase oil in U.S. Pat. No. 6,332,974. That oil had anexemplary VI of as high as 148 and a low pour point. Relatedly, in U.S.Pat. No. 6,610,636, another premium synthetic lubricant was demonstratedto have antiwear properties that are desirable for internal combustionengine oils. That oil comprised a FTBO having an exemplary VI of as highas 138, and at least one antiwear additive.

In U.S. Pat. No. 6,090,758, yet another crankcase oil for internalcombustion engines was disclosed to comprise liquid wax isomerate as abase stock, such as one that is synthesized from the Fischer-Tropschprocesses. That crankcase oil was again said to have an exemplary VI ofas high as 138, a significantly greater VI as compared to an oilprepared from conventional, petroleum derived base stocks, and haveimproved antifoaming properties.

However, the harsh operating conditions to which a turbine oil issubjected and the large sump volumes place demands on the oil that arevery different from those placed on a non-turbine lubricant oil. Variousblended oils comprising one or more PAOs in addition to one or moreFTBOs have been prepared to achieve VIs as high as greater than 150. Forexample, in published U.S. Applications 2006/0196807 A1 and 2006/0199743A1, blended base oils comprising an FTBO and a PAO lubricant base oilwere used to achieve superior wear protection, oxygen stability, lowpour point, low volatility, and a VI of greater than 140, and morepreferably greater than 165. This approach, however, is not favored inview of the potentially dramatic cost increase associated with usingeven a small amount of PAOs in an oil.

Accordingly, in its broadest embodiment, the present invention pertainsto a turbine oil composition comprising a major amount of an FTBO or ablend of more than one FTBOs, and one or more standard turbine oiladditive packages, wherein the finished turbine oil composition has a VIof greater than about 150. The present invention also pertains to themethod of making and using such a composition. The turbine oilcomposition provides an economically acceptable and effective means tolubricate a wide spectrum of modern industrial turbines. The VIs of thethese turbine oil compositions are typically above about 150, or aboveabout 153, or above about 155, or above about 158, or even above about160, rendering them suitable for use with steam turbines and gasturbines wherein the bearings are exposed to wide range of temperatures.Compared to turbine oils that comprise only non-FTBOs, the compositionalso demonstrates improved oxidative stability, which will in turnenhance its service life, making it feasible to change oil lessfrequently. The composition has an improved flash point, typically aboveabout 236° C., or above about 238° C., or above about 240° C., or aboveabout 245° C., or even above about 250° C., thus rendering a relativelylow tendency to catch fire under high temperatures. The oil furtherpossesses improved capacity to release entrained air, thus reducingharmful foaming and sludge formation when water is present as acontaminant in the operation environment, especially when used tolubricate a hydraulic turbine.

SUMMARY

In a first aspect, the present turbine oil composition comprises: amajor amount of one or more isomerized base oils; a minor amount of astandard turbine oil additive; wherein the turbine oil composition has aVI of greater than 150.

The turbine oil composition of this aspect may optionally comprise oneor more other base oils, so long as those other base oils do notnegatively affect the VI, oxidative stability, sludge formationtendency, flash point, and capacity to release entrained air of theturbine oil composition. By “negatively affect,” it is meant that theabove-stated properties is to any extent impaired, as measured byart-accepted turbine compressor or bench tests indicating suchproperties and designed to mimic the conditions under which industrialturbines typically operate.

In a second aspect, the application provides a method of preparing aturbine oil composition of the first aspect.

In a third aspect, the application provides a method of operating anindustrial turbine, which method comprises lubricating the bearings andparts of said turbine with a lubricating composition of the firstaspect.

DETAILED DESCRIPTION

The following terms will be used throughout the specification and willhave the following meanings unless otherwise indicated.

“Fischer-Tropsch derived” means that the product, fraction, or feedoriginates from or is produced at some stage by a Fischer-Tropschprocess. As used herein, “Fischer-Tropsch base oil” may be usedinterchangeably with “FT base oil,” “FTBO,” “GTL base oil” (GTL:gas-to-liquid), or “Fischer-Tropsch derived base oil.”

As used herein, “isomerized base oil” refers to a base oil made byisomerization of a waxy feed. In one embodiment, the isomerized base oilis a Fischer-Tropsch derived base oil.

As used herein, a “waxy feed” comprises at least 40 wt % n-paraffins. Inone embodiment, the waxy feed comprises greater than 50 wt %n-paraffins. In another embodiment, greater than 75 wt % n-paraffins. Inone embodiment, the waxy feed also has very low levels of nitrogen andsulphur, e.g., less than 25 ppm total combined nitrogen and sulfur, orin other embodiments less than 20 ppm. Examples of waxy feeds includeslack waxes, deoiled slack waxes, refined foots oils, waxy lubricantraffinates, n-paraffin waxes, NAO waxes, waxes produced in chemicalplant processes, deoiled petroleum derived waxes, microcrystallinewaxes, Fischer-Tropsch waxes, and mixtures thereof. In one embodiment,the waxy feeds have a pour point of greater than 50° C. In anotherembodiment, greater than 60° C.

“Kinematic viscosity” is a measurement in mm²/s of the resistance toflow of a fluid under gravity, determined by ASTM D445-06.

“Viscosity index” (VI) is an empirical, unit-less number indicating theeffect of temperature change on the kinematic viscosity of the oil. Thehigher the VI of an oil, the lower its tendency to change viscosity withtemperature. Viscosity index is measured according to ASTM D 2270-04.

Cold-cranking simulator apparent viscosity (CCS VIS) is a measurement inmillipascal seconds, mPa·s to measure the viscometric properties oflubricating base oils under low temperature and low shear. CCS VIS isdetermined by ASTM D 5293-04.

The boiling range distribution of base oil, by wt %, is determined bysimulated distillation (SIMDIS) according to ASTM D 6352-04, “BoilingRange Distribution of Petroleum Distillates in Boiling Range from 174 to700° C. by Gas Chromatography.”

“Noack volatility” is defined as the mass of oil, expressed in weight %,which is lost when the oil is heated at 250° C. with a constant flow ofair drawn through it for 60 min., measured according to ASTM D5800-05,Procedure B.

Brookfield viscosity is used to determine the internal fluid-friction ofa lubricant during cold temperature operation, which can be measured byASTM D 2983-04.

“Pour point” is a measurement of the temperature at which a sample ofbase oil will begin to flow under certain carefully controlledconditions, which can be determined as described in ASTM D 5950-02.

“Auto ignition temperature” is the temperature at which a fluid willignite spontaneously in contact with air, which can be determinedaccording to ASTM E 659 (Rev. 2005).

“Ln” refers to natural logarithm with base “e.”

“Traction coefficient” is an indicator of intrinsic lubricantproperties, expressed as the dimensionless ratio of the friction force Fand the normal force N, where friction is the mechanical force whichresists movement or hinders movement between sliding or rollingsurfaces. Traction coefficient can be measured with an MTM TractionMeasurement System from PCS Instruments, Ltd., configured with apolished 19 mm diameter ball (SAE AISI 52100 steel) angled at 220 to aflat 46 mm diameter polished disk (SAE AISI 52100 steel). The steel balland disk are independently measured at an average rolling speed of 3meters per second, a slide to roll ratio of 40 percent, and a load of 20Newtons. The roll ratio is defined as the difference in sliding speedbetween the ball and disk divided by the mean speed of the ball anddisk, i.e. roll ratio=(Speed1−Speed2)/((Speed1+Speed2)−/2).

As used herein, “consecutive numbers of carbon atoms” means that thebase oil has a distribution of hydrocarbon molecules over a range ofcarbon numbers, with every number of carbon numbers in-between. Forexample, the base oil may have hydrocarbon molecules ranging from C22 toC36 or from C30 to C60 with every carbon number in-between. Thehydrocarbon molecules of the base oil differ from each other byconsecutive numbers of carbon atoms, as a consequence of the waxy feedalso having consecutive numbers of carbon atoms. For example, in theFischer-Tropsch hydrocarbon synthesis reaction, the source of carbonatoms is CO and the hydrocarbon molecules are built up one carbon atomat a time. Petroleum-derived waxy feeds have consecutive numbers ofcarbon atoms. In contrast to an oil based on poly-alpha-olefin (“PAO”),the molecules of an isomerized base oil have a more linear structure,comprising a relatively long backbone with short branches. The classictextbook description of a PAO is a star-shaped molecule, and inparticular tridecane, which is illustrated as three decane moleculesattached at a central point. While a star-shaped molecules istheoretical, nevertheless PAO molecules have fewer and longer branchesthat the hydrocarbon molecules that make up the isomerized base oildisclosed herein.

“Molecules with cycloparaffinic functionality” mean any molecule thatis, or contains as one or more substituents, a monocyclic or a fusedmulticyclic saturated hydrocarbon group.

“Molecules with monocycloparaffinic functionality” mean any moleculethat is a monocyclic saturated hydrocarbon group of three to seven ringcarbons or any molecule that is substituted with a single monocyclicsaturated hydrocarbon group of three to seven ring carbons.

“Molecules with multicycloparaffinic functionality” mean any moleculethat is a fused multicyclic saturated hydrocarbon ring group of two ormore fused rings, any molecule that is substituted with one or morefused multicyclic saturated hydrocarbon ring groups of two or more fusedrings, or any molecule that is substituted with more than one monocyclicsaturated hydrocarbon group of three to seven ring carbons.

Molecules with cycloparaffinic functionality, molecules withmonocycloparaffinic functionality, and molecules withmulticycloparaffinic functionality are reported as weight percent andare determined by a combination of Field Ionization Mass Spectroscopy(FIMS), HPLC-UV for aromatics, and Proton NMR for olefins, further fullydescribed herein.

Oxidator BN measures the response of a lubricating oil in a simulatedapplication. High values, or long times to adsorb one liter of oxygen,indicate good stability. Oxidator BN can be measured via a Dornte-typeoxygen absorption apparatus (R. W. Domte “Oxidation of White Oils,”Industrial and Engineering Chemistry, Vol. 28, page 26, 1936), under 1atmosphere of pure oxygen at 340° F., time to absorb 1000 ml of O₂ by100 g. of oil is reported. In the Oxidator BN test, 0.8 ml of catalystis used per 100 grams of oil. The catalyst is a mixture of solublemetal-naphthenates simulating the average metal analysis of usedcrankcase oil. The additive package is 80 millimoles of zincbispolypropylenephenyldithiophosphate per 100 grams of oil.

Molecular characterizations can be performed by methods known in theart, including Field Ionization Mass Spectroscopy (FIMS) and n-d-Manalysis (ASTM D 3238-95 (Re-approved 2005) with normalization). InFIMS, the base oil is characterized as alkanes and molecules withdifferent numbers of unsaturations. The molecules with different numbersof unsaturations may be comprised of cycloparaffins, olefins, andaromatics. If aromatics are present in significant amount, they would beidentified as 4-unsaturations. When olefins are present in significantamounts, they would be identified as 1-unsaturations. The total of the1-unsaturations, 2-unsaturations, 3-unsaturations, 4-unsaturations,5-unsaturations, and 6-unsaturations from the FIMS analysis, minus thewt % olefins by proton NMR, and minus the wt % aromatics by HPLC-UV isthe total weight percent of molecules with cycloparaffinicfunctionality. If the aromatics content was not measured, it was assumedto be less than 0.1 wt % and not included in the calculation for totalweight percent of molecules with cycloparaffinic functionality. Thetotal weight percent of molecules with cycloparaffinic functionality isthe sum of the weight percent of molecules with monocyclopraffinicfunctionality and the weight percent of molecules withmulticycloparaffinic functionality.

Molecular weights are determined by ASTM D2503-92(Reapproved 2002). Themethod uses thermoelectric measurement of vapour pressure (VPO). Incircumstances where there is insufficient sample volume, an alternativemethod of ASTM D2502-04 may be used; and where this has been used it isindicated.

Density is determined by ASTM D4052-96 (Reapproved 2002). The sample isintroduced into an oscillating sample tube and the change in oscillatingfrequency caused by the change in the mass of the tube is used inconjunction with calibration data to determine the density of thesample. Weight percent olefins can be determined by proton-NMR accordingto the steps specified herein. In most tests, the olefins areconventional olefins, i.e. a distributed mixture of those olefin typeshaving hydrogens attached to the double bond carbons such as: alpha,vinylidene, cis, trans, and tri-substituted, with a detectable allylicto olefin integral ratio between 1 and 2.5. When this ratio exceeds 3,it indicates a higher percentage of tri or tetra substituted olefinsbeing present, thus other assumptions known in the analytical art can bemade to calculate the number of double bonds in the sample. The stepsare as follows: A) Prepare a solution of 5-10% of the test hydrocarbonin deuterochloroform. B) Acquire a normal proton spectrum of at least 12ppm spectral width and accurately reference the chemical shift (ppm)axis, with the instrument having sufficient gain range to acquire asignal without overloading the receiver/ADC, e.g., when a 30 degreepulse is applied, the instrument having a minimum signal digitizationdynamic range of 65,000. In one embodiment, the instrument has a dynamicrange of at least 260,000. C) Measure the integral intensities between:6.0-4.5 ppm (olefin); 2.2-1.9 ppm (allylic); and 1.9-0.5 ppm (saturate).D) Using the molecular weight of the test substance determined by ASTM D2503-92 (Reapproved 2002), calculate: 1. The average molecular formulaof the saturated hydrocarbons; 2. The average molecular formula of theolefins; 3. The total integral intensity (=sum of all integralintensities); 4. The integral intensity per sample hydrogen (=totalintegral/number of hydrogens in formula); 5. The number of olefinhydrogens (=Olefin integral/integral per hydrogen); 6. The number ofdouble bonds (=Olefin hydrogen times hydrogens in olefin formula/2); and7. The wt % olefins by proton NMR=100 times the number of double bondstimes the number of hydrogens in a typical olefin molecule divided bythe number of hydrogens in a typical test substance molecule. In thistest, the wt % olefins by proton NMR calculation procedure, D, worksparticularly well when the percent olefins result is low, less than 15wt %.

Weight percent aromatics in one embodiment can be measured by HPLC-UV.In one embodiment, the test is conducted using a Hewlett Packard 1050Series Quaternary Gradient High Performance Liquid Chromatography (HPLC)system, coupled with a HP 1050 Diode-Array UV-Vis detector interfaced toan HP Chem-station. Identification of the individual aromatic classes inthe highly saturated base oil can be made on the basis of the UVspectral pattern and the elution time. The amino column used for thisanalysis differentiates aromatic molecules largely on the basis of theirring-number (or double-bond number). Thus, the single ring aromaticcontaining molecules elute first, followed by the polycyclic aromaticsin order of increasing double bond number per molecule. For aromaticswith similar double bond character, those with only alkyl substitutionon the ring elute sooner than those with naphthenic substitution.Unequivocal identification of the various base oil aromatic hydrocarbonsfrom their UV absorbance spectra can be accomplished recognizing thattheir peak electronic transitions are all red-shifted relative to thepure model compound analogs to a degree dependent on the amount of alkyland naphthenic substitution on the ring system. Quantification of theeluting aromatic compounds can be made by integrating chromatograms madefrom wavelengths optimized for each general class of compounds over theappropriate retention time window for that aromatic. Retention timewindow limits for each aromatic class can be determined by manuallyevaluating the individual absorbance spectra of eluting compounds atdifferent times and assigning them to the appropriate aromatic classbased on their qualitative similarity to model compound absorptionspectra. Weight percent aromatic carbon (“Ca”), weight percentnaphthenic carbon (“Cn”) and weight percent paraffinic carbon (“Cp”) inone embodiment can be measured by ASTM D3238-95 (Reapproved 2005) withnormalization. ASTM D3238-95 (Reapproved 2005) is the Standard TestMethod for Calculation of Carbon Distribution and Structural GroupAnalysis of Petroleum Oils by the n-d-M Method. This method is for“olefin free” feedstocks which are assumed in this application to meanthat that olefin content is 2 wt % or less. The normalization processconsists of the following: A) If the Ca value is less than zero, Ca isset to zero, and Cn and Cp are increased proportionally so that the sumis 100%. B) If the Cn value is less than zero, Cn is set to zero, and Caand Cp are increased proportionally so that the sum is 100%; and C) Ifboth Cn and Ca are less than zero, Cn and Ca are set to zero, and Cp isset to 100%.

HPLC-UV Calibration. In one embodiment, HPLC-UV can be used foridentifying classes of aromatic compounds even at very low levels, e.g.,multi-ring aromatics typically absorb 10 to 200 times more strongly thansingle-ring aromatics. Alkyl-substitution affects absorption by 20%.Integration limits for the co-eluting 1-ring and 2-ring aromatics at 272nm can be made by the perpendicular drop method. Wavelength dependentresponse factors for each general aromatic class can be first determinedby constructing Beer's Law plots from pure model compound mixtures basedon the nearest spectral peak absorbances to the substituted aromaticanalogs. Weight percent concentrations of aromatics can be calculated byassuming that the average molecular weight for each aromatic class wasapproximately equal to the average molecular weight for the whole baseoil sample.NMR analysis. In one embodiment, the weight percent of allmolecules with at least one aromatic function in the purifiedmono-aromatic standard can be confirmed via long-duration carbon 13 NMRanalysis. The NMR results can be translated from % aromatic carbon to %aromatic molecules (to be consistent with HPLC-UV and D 2007) knowingthat 95-99% of the aromatics in highly saturated base oils aresingle-ring aromatics. In another test to accurately measure low levelsof all molecules with at least one aromatic function by NMR, thestandard D 5292-99 (Reapproved 2004) method can be modified to give aminimum carbon sensitivity of 500:1 (by ASTM standard practice E 386)with a 15-hour duration run on a 400-500 MHz NMR with a 10-12 mm Naloracprobe. Acorn PC integration software can be used to define the shape ofthe baseline and consistently integrate.

Extent of branching refers to the number of alkyl branches inhydrocarbons. Branching and branching position can be determined usingcarbon-13 (¹³C) NMR according to the following nine-step process: 1)Identify the CH branch centers and the CH₃ branch termination pointsusing the DEPT Pulse sequence (Doddrell, D. T.; D. T. Pegg; M. R.Bendall, Journal of Magnetic Resonance 1982, 48, 323ff.). 2) Verify theabsence of carbons initiating multiple branches (quaternary carbons)using the APT pulse sequence (Patt, S. L.; J. N. Shoolery, Journal ofMagnetic Resonance 1982, 46, 535ff.). 3) Assign the various branchcarbon resonances to specific branch positions and lengths usingtabulated and calculated values known in the art (Lindeman, L. P.,Journal of Qualitative Analytical Chemistry 43, 1971 1245ff; Netzel, D.A., et.al., Fuel, 60, 1981, 307ff). 4) Estimate relative branchingdensity at different carbon positions by comparing the integratedintensity of the specific carbon of the methyl/alkyl group to theintensity of a single carbon (which is equal to total integral/number ofcarbons per molecule in the mixture). For the 2-methyl branch, whereboth the terminal and the branch methyl occur at the same resonanceposition, the intensity is divided by two before estimating thebranching density. If the 4−methyl branch fraction is calculated andtabulated, its contribution to the 4+methyls is subtracted to avoiddouble counting. 5) Calculate the average carbon number. The averagecarbon number is determined by dividing the molecular weight of thesample by 14 (the formula weight of CH₂). 6) The number of branches permolecule is the sum of the branches found in step 4. 7) The number ofalkyl branches per 100 carbon atoms is calculated from the number ofbranches per molecule (step 6) times 100/average carbon number. 8)Estimate Branching Index (BI) by ¹H NMR Analysis, which is presented aspercentage of methyl hydrogen (chemical shift range 0.6-1.05 ppm) amongtotal hydrogen as estimated by NMR in the liquid hydrocarboncomposition. 9) Estimate Branching proximity (BP) by ¹³C NMR, which ispresented as percentage of recurring methylene carbons—which are four ormore carbons away from the end group or a branch (represented by a NMRsignal at 29.9 ppm) among total carbons as estimated by NMR in theliquid hydrocarbon composition. The measurements can be performed usingany Fourier Transform NMR spectrometer, e.g., one having a magnet of 7.0T or greater. After verification by Mass Spectrometry, UV or an NMRsurvey that aromatic carbons are absent, the spectral width for the ¹³CNMR studies can be limited to the saturated carbon region, 0-80 ppm vs.TMS (tetramethylsilane). Solutions of 25-50 wt. % in chloroform-dl areexcited by 30 degrees pulses followed by a 1.3 seconds (sec.)acquisition time. In order to minimize non-uniform intensity data, thebroadband proton inverse-gated decoupling is used during a 6 sec. delayprior to the excitation pulse and on during acquisition. Samples aredoped with 0.03 to 0.05 M Cr (acac)₃ (tris (acetylacetonato)-chromium(III)) as a relaxation agent to ensure full intensities are observed.The DEPT and APT sequences can be carried out according to literaturedescriptions with minor deviations described in the Varian or Brukeroperating manuals. DEPT is Distortionless Enhancement by PolarizationTransfer. The DEPT 45 sequence gives a signal all carbons bonded toprotons. DEPT 90 shows CH carbons only. DEPT 135 shows CH and CH₃ up andCH₂ 180 degrees out of phase (down). APT is attached proton test, knownin the art. It allows all carbons to be seen, but if CH and CH₃ are up,then quaternaries and CH₂ are down. The branching properties of thesample can be determined by ¹³C NMR using the assumption in thecalculations that the entire sample was iso-paraffinic.

Oil of Lubricating viscosity. In one embodiment, the turbine oilcomposition comprises a major amount of one or more base oils.Generally, the total amount of one or more base oils constitutes greaterthan about 60 wt. %, 70 wt. %, 80 wt. %, 90 wt. %, or 95 wt. % of thefinished turbine oil composition (“a major amount”). In one embodimentwhen a single base oil is present in the turbine oil, that single baseoil is an isomerized base oil. When more than one base oils are present,at least one of these base oils is an isomerized base oil.

Isomerized Base Oil Component. In one embodiment, the base oil or blendthereof comprises at least an isomerized base oil which the productitself, its fraction, or feed originates from or is produced at somestage by isomerization of a waxy feed from a Fischer-Tropsch process(“Fischer-Tropsch derived base oils”). In another embodiment, the baseoil comprises at least an isomerized base oil made from a substantiallyparaffinic wax feed (“waxy feed”). In a third embodiment, the isomerizedbase oil comprises mixtures of products made from a substantiallyparaffinic wax feed as well as products made from a waxy feed from aFischer-Tropsch process.

Fischer-Tropsch derived base oils are disclosed in a number of patentpublications, including for example U.S. Pat. Nos. 6,080,301, 6,090,989,and 6165949, and US Patent Publication No. US2004/0079678A1,US20050133409, US20060289337. The Fischer-Tropsch process is a catalyzedchemical reaction in which carbon monoxide and hydrogen are convertedinto liquid hydrocarbons of various forms including a light reactionproduct and a waxy reaction product, with both being substantiallyparaffinic.

In one embodiment the isomerized base oil has consecutive numbers ofcarbon atoms and has less than 25 wt % naphthenic carbon by n-d-M withnormalization. In another embodiment, the amount of naphthenic carbon isless than 10 wt. %. In yet another embodiment the isomerized base oilmade from a waxy feed has a kinematic viscosity at 100° C. between 1.5and 3.5 mm²/s.

In one embodiment, the isomerized base oil is made by a process in whichthe hydroisomerization dewaxing is performed at conditions sufficientfor the base oil to have: a) a weight percent of all molecules with atleast one aromatic functionality less than 0.30; b) a weight percent ofall molecules with at least one cycloparaffinic functionality greaterthan 10; c) a ratio of weight percent molecules with monocycloparaffinicfunctionality to weight percent molecules with multicycloparaffinicfunctionality greater than 20 and d) a viscosity index greater than28×Ln (Kinematic viscosity at 100° C.)+80.

In another embodiment, the isomerized base oil is made from a process inwhich the highly paraffinic wax is hydroisomerized using a shapeselective intermediate pore size molecular sieve comprising a noblemetal hydrogenation component, and under conditions of 600-750° F.(315-399° C.) In the process, the conditions for hydroisomerization arecontrolled such that the conversion of the compounds boiling above 700°F. (371° C.) in the wax feed to compounds boiling below 700° F. (371°C.) is maintained between 10 wt % and 50 wt %. A resulting isomerizedbase oil has a kinematic viscosity of between 1.0 and 3.5 mm²/s at 100°C. and a Noack volatility of less than 50 weight %. The base oilcomprises greater than 3 weight % molecules with cycloparaffinicfunctionality and less than 0.30 weight percent aromatics.

In one embodiment the isomerized base oil has a Noack volatility lessthan an amount calculated by the following equation: 1000×(KinematicViscosity at 100° C.)^(−2.7). In another embodiment, the isomerized baseoil has a Noack volatility less than an amount calculated by thefollowing equation: 900×(Kinematic Viscosity at 100° C.)^(−2.8). In athird embodiment, the isomerized base oil has a Kinematic Viscosity at100° C. of >1.808 mm²/s and a Noack volatility less than an amountcalculated by the following equation: 1.286+20 (kv100)^(−1.5)+551.8e^(−kv100), where kv100 is the kinematic viscosity at 100° C. In afourth embodiment, the isomerized base oil has a kinematic viscosity at100° C. of less than 4.0 mm²/s, and a wt % Noack volatility between 0and 100. In a fifth embodiment, the isomerized base oil has a kinematicviscosity between 1.5 and 4.0 mm²/s and a Noack volatility less than theNoack volatility calculated by the following equation: 160-40 (KinematicViscosity at 100° C.).

In one embodiment, the isomerized base oil has a kinematic viscosity at100° C. in the range of 2.4 and 3.8 mm²/s and a Noack volatility lessthan an amount defined by the equation: 900×(Kinematic Viscosity at 100°C.)^(−2.8)−15). For kinematic viscosities in the range of 2.4 and 3.8mm²/s, the equation: 900×(Kinematic Viscosity at 100° C.)^(−2.8)−15)provides a lower Noack volatility than the equation: 160-40 (KinematicViscosity at 100° C.)

In one embodiment, the isomerized base oil is made from a process inwhich the highly paraffinic wax is hydroisomerized under conditions forthe base oil to have a kinematic viscosity at 100° C. of 3.6 to 4.2mm²/s, a viscosity index of greater than 130, a wt % Noack volatilityless than 12, a pour point of less than −9° C.

In one embodiment, the isomerized base oil has an aniline point, indegrees F., greater than 200 and less than or equal to an amount definedby the equation: 36×Ln(Kinematic Viscosity at 100° C., in mm²/s)+200.

In one embodiment, the isomerized base oil has an auto-ignitiontemperature (AIT) greater than the AIT defined by the equation: AIT in °C.=1.6×(Kinematic Viscosity at 40° C., in mm²/s)+300. In a secondembodiment, the base oil as an AIT of greater than 329° C. and aviscosity index greater than 28×Ln (Kinematic Viscosity at 100° C., inmm²/s)+100.

In one embodiment, the isomerized base oil has a relatively low tractioncoefficient, specifically, its traction coefficient is less than anamount calculated by the equation: traction coefficient=0.009×Ln(kinematic viscosity in mm²/s)−0.001, wherein the kinematic viscosity inthe equation is the kinematic viscosity during the traction coefficientmeasurement and is between 2 and 50 mm²/s. In one embodiment, theisomerized base oil has a traction coefficient of less than 0.023 (orless than 0.021) when measured at a kinematic viscosity of 15 mm²/s andat a slide to roll ratio of 40%. In another embodiment the isomerizedbase oil has a traction coefficient of less than 0.017 when measured ata kinematic viscosity of 15 mm²/s and at a slide to roll ratio of 40%.In another embodiment the isomerized base oil has a viscosity indexgreater than 150 and a traction coefficient less than 0.015 whenmeasured at a kinematic viscosity of 15 mm²/s and at a slide to rollratio of 40 percent.

In some embodiments, the isomerized base oil having low tractioncoefficients also displays a higher kinematic viscosity and higherboiling points. In one embodiment, the base oil has a tractioncoefficient less than 0.015, and a 50 wt % boiling point greater than565° C. (1050° F.). In another embodiment, the base oil has a tractioncoefficient less than 0.011 and a 50 wt % boiling point by ASTM D6352-04 greater than 582° C. (1080° F.).

In some embodiments, the isomerized base oil having low tractioncoefficients also displays unique branching properties by NMR, includinga branching index less than or equal to 23.4, a branching proximitygreater than or equal to 22.0, and a Free Carbon Index between 9 and 30.In one embodiment, the base oil has at least 4 wt % naphthenic carbon,in another embodiment, at least 5 wt % naphthenic carbon by n-d-Manalysis by ASTM D 3238-95 (Reapproved 2005) with normalization.

In one embodiment, the isomerized base oil is produced in a processwherein the intermediate oil isomerate comprises paraffinic hydrocarboncomponents, and in which the extent of branching is less than 7 alkylbranches per 100 carbons, and wherein the base oil comprises paraffinichydrocarbon components in which the extent of branching is less than 8alkyl branches per 100 carbons and less than 20 wt % of the alkylbranches are at the 2 position. In one embodiment, the FT base oil has apour point of less than −8° C.; a kinematic viscosity at 100° C. of atleast 3.2 mm²/s; and a viscosity index greater than a viscosity indexcalculated by the equation of =22×Ln (kinematic viscosity at 100°C.)+132.

In one embodiment, the base oil comprises greater than 10 wt. % and lessthan 70 wt. % total molecules with cycloparaffinic functionality, and aratio of weight percent molecules with monocycloparaffinic functionalityto weight percent molecules with multicycloparaffinic functionalitygreater than 15.

In one embodiment, the isomerized base oil has an average molecularweight between 600 and 1100, and an average degree of branching in themolecules between 6.5 and 10 alkyl branches per 100 carbon atoms. Inanother embodiment, the isomerized base oil has a kinematic viscositybetween about 8 and about 25 mm²/s and an average degree of branching inthe molecules between 6.5 and 10 alkyl branches per 100 carbon atoms.

In one embodiment, the isomerized base oil is obtained from a process inwhich the highly paraffinic wax is hydroisomerized at a hydrogen to feedratio from 712.4 to 3562 liter H₂/liter oil, for the base oil to have atotal weight percent of molecules with cycloparaffinic functionality ofgreater than 10, and a ratio of weight percent molecules withmonocycloparaffinic functionality to weight percent molecules withmulticycloparaffinic functionality of greater than 15. In anotherembodiment, the base oil has a viscosity index greater than an amountdefined by the equation: 28×Ln (Kinematic viscosity at 100° C.)+95. In athird embodiment, the base oil comprises a weight percent aromatics lessthan 0.30; a weight percent of molecules with cycloparaffinicfunctionality greater than 10; a ratio of weight percent of moleculeswith monocycloparaffinic functionality to weight percent of moleculeswith multicycloparaffinic functionality greater than 20; and a viscosityindex greater than 28×Ln (Kinematic Viscosity at 100° C.)+110. In afourth embodiment, the base oil further has a kinematic viscosity at100° C. greater than 6 mm²/s. In a fifth embodiment, the base oil has aweight percent aromatics less than 0.05 and a viscosity index greaterthan 28×Ln (Kinematic Viscosity at 100° C.)+95. In a sixth embodiment,the base oil has a weight percent aromatics less than 0.30, a weightpercent molecules with cycloparaffinic functionality greater than thekinematic viscosity at 100° C., in mm²/s, multiplied by three, and aratio of molecules with monocycloparaffinic functionality to moleculeswith multicycloparaffinic functionality greater than 15.

In one embodiment, the isomerized base oil contains between 2 and 10 wt% naphthenic carbon as measured by n-d-M. In one embodiment, the baseoil has a kinematic viscosity of 1.5-3.0 mm²/s at 100° C. and 2-3 wt %naphthenic carbon. In another embodiment, a kinematic viscosity of1.8-3.5 mm²/s at 100° C. and 2.5-4 wt % naphthenic carbon. In a thirdembodiment, a kinematic viscosity of 3-6 mm²/s at 100° C. and 2.7-5 wt %naphthenic carbon. In a fourth embodiment, a kinematic viscosity of10-30 mm²/s at 100° C. and between greater than 5.2% and less than 25 wt% naphthenic carbon.

In one embodiment, the isomerized base oil has an average molecularweight greater than 475; a viscosity index greater than 140, and aweight percent olefins less than 10. The base oil improves the airrelease and low foaming characteristics of the mixture when incorporatedinto the turbine oil composition.

In one embodiment, the isomerized base oil is a white oil as disclosedin U.S. Pat. No. 7,214,307 and US Patent Publication US20060016724. Inone embodiment, the isomerized base oil is a white oil having akinematic viscosity at 100° C. between about 1.5 cSt and 36 mm²/s, aviscosity index greater than an amount calculated by the equation:Viscosity Index=28×Ln(the Kinematic Viscosity at 100° C.)+95, between 5and less than 18 weight percent molecules with cycloparaffinicfunctionality, less than 1.2 weight percent molecules withmulticycloparaffinic functionality, a pour point less than 0° C. and aSaybolt color of +20 or greater.

In one embodiment, the composition comprises at least an isomerized baseoil in a major amount (i.e., an amount greater than about 50 wt. %).Generally, the total amount of isomerized base oils is greater thanabout 60 wt. %, or greater than about 70 wt. %, or greater than about 80wt. % of the turbine oil composition. In yet another embodiment, theturbine oil composition comprises about 79 wt. % of a base oil mixture,which in turn comprises two different isomerized base oils.

If two or more isomerized base oils are blended into one base oilmixture, the amounts of each isomerized base oil can be in anyproportion so that the finished oil has the desired viscosity and VI, asdescribed herein. When two isomerized base oils are blended into onebase oil mixture, for example, that proportion may be from 10:90 to90:10, or from 20:80 to 80:20, such as from 30:70 to 70:30. An exemplarycomposition comprises two isomerized base oils blended in a proportionof about 35:65, yielding a kinematic viscosity of about 30 mm²/s at 40°C., and a VI of about 160.

In one embodiment, the turbine oil composition comprises two isomerizedbase oils, the first having a pour point of about −18° C., and thesecond having a pour point of about −13° C. In yet another embodiment,the composition comprises two isomerized base oils, with the firsthaving a cloud point of about −12° C., and the second having a cloudpoint of about 5° C.

In one embodiment for general application in a non-turbine equipment, itis desired that the Oxidator BN of a lubricant base oil be greater thanabout 7 hours. In another embodiment for a turbine oil, it is oftendesired that the Oxidator BN of the base oil be at or above about 30hours. In one embodiment, the composition comprises an isomerized baseoil having Oxidator BN of about 44 hours. Another exemplary isomerizedbase oil in yet another embodiment has an Oxidator BN of about 45.4hours.

Other Non-Isomerized Base Oil Components (“Non-FTBO”). In oneembodiment, the composition employs a base oil that consists of at leastone of the isomerized base oils described above. In another embodiment,the composition consists essentially of at least a Fischer-Tropsch baseoil. In yet another embodiment, the composition employs at least aFischer-Tropsch base oil and one or more additional base oils selectedfrom: natural oils, synthetic oils, and mixtures thereof, provided thatthe finished turbine oil has a VI of greater than 150. Moreover, if oneor more additional base oils (i.e., other than the isomerized base oils)are present, these additional base oils do not negatively affect theimprovements conferred by the isomerized base oils in VI, oxidativestability, fire resistance, air release capacity, and foam- andsludge-forming tendencies.

The natural oils that are suitable include animal oils and vegetableoils (e.g., castor oil, lard oil). The natural oils may also includemineral lubricating oils such as liquid petroleum oils andsolvent-treated or acid-treated mineral lubricating oils of theparaffinic, naphthenic or mixed paraffinic-naphthenic types. Oilsderived from coal or shale are also useful.

Synthetic non-FTBOs include alkylene oxide polymers and interpolymersand derivatives thereof where the terminal hydroxyl groups have beenmodified by a process such as esterification or etherification. Examplesof these synthetic oils include polyoxyalkylene polymers prepared bypolymerization of ethylene oxide or propylene oxide, and the alkyl andaryl ethers of polyoxyalkylene polymers (e.g., methyl-polyiso-propyleneglycol ether having a molecular weight of 1000 Daltons or diphenyl etherof poly-ethylene glycol having a molecular weight of 1000 to 1500Daltons); and mono- and polycarboxylic esters thereof (e.g., acetic acidesters, mixed C₃-C₈ fatty acid esters, and C₁₃ Oxo acid diester oftetraethylene glycol). Other suitable synthetic oils includepolyisobutenes, and alkylated aromatics such as alkylated naphthalenes.

Another suitable class of synthetic lubricating oils are the esters ofdicarboxylic acids (e.g., phthalic acid, succinic acid, alkyl succinicacids and alkenyl succinic acids, maleic acid, azelaic acid, subericacid, sebasic acid, fumaric acid, adipic acid, linoleic acid dimer,malonic acid, alkylmalonic acids, alkenyl malonic acids) with a varietyof alcohols (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol,2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether,propylene glycol). Specific examples of such esters includes dibutyladipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctylsebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate,didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester oflinoleic acid dimer, and the complex ester formed by reacting one moleof sebacic acid with two moles of tetraethylene glycol and two moles of2-ethylhexanoic acid and the like. Esters useful as synthetic oils alsoinclude those made from C₅ to C₁₂ monocarboxylic acids and polyols andpolyol esters such as neopentyl glycol, trimethylolpropane,pentaerythritol, dipentaerythritol and tripentaerythritol.

The synthetic oil can also be a poly-alpha-olefin (PAO) when used in avery small amount. Typically, the PAOs are derived from monomers havingfrom 4 to 30, or from 4 to 20, or from 6 to 16 carbon atoms. Examples ofuseful PAOs include those derived from α-octene, α-decene, mixturesthereof, and the like. Mixtures of mineral oil with one or more of theforegoing PAOs may also be used. Regardless whether a single PAO or amixture of PAOs is used, however, the total amount should be keptrelatively low, such as less than about 10 wt. %, or less than about 5wt. %, or less than about 2 wt. %, or even less than about 1 wt. %, suchas less than about 0.1 wt. %, so as to provide a turbine oil of lowcost.

Unrefined, refined and rerefined oils, either natural or synthetic (aswell as mixtures of two or more) of the types of oils disclosed abovecan be used in the lubricating compositions. Unrefined (or raw) oils arethose obtained directly from a natural or synthetic source withoutfurther purification treatment. Refined oils are similar-to theunrefined oils except they have been further treated in one or morepurification steps. Many such purification techniques are known to thoseskilled in the art such as solvent extraction, secondary distillation,acid or base extraction, filtration, percolation, and the like.Rerefined oils are oils that have been used in service but aresubsequently treated so that they may be re-applied in service. Becausethe used oils almost always contain spent additives and breakdownproducts, in addition to the standard oil refining steps, steps thatwould remove the spent additives and breakdown products must be taken.Such rerefined oils are also known as reclaimed or reprocessed oils.

Standard Turbine Oil Additive Packages The turbine oil composition mayfurther comprise an effective amount of one or more standard turbine oiladditive packages in an amount of 5-40 wt. % of the finished turbine oilcomposition (“a minor amount”). Many of those packages are known andcommercially available. Each of these packages typically comprise one ormore antioxidants, one or more rust/corrosion inhibitors, and one ormore antifoamants, and one or more other additives including, forexample, viscosity index improvers, wear inhibitors, and/ordemulsifiers.

Antioxidants Antioxidants are chemicals that reduce the tendency ofmineral oils to deteriorate in service. They extend the life of thelubricant fluid by interrupting the oxidation process, e.g., bydecomposing hydroperoxide intermediates (ROOH, where R is an alkylchain) and scavenging free radicals. One known type of antioxidants arealkaline earth metal salts of alkylphenolthioesters having preferably C₅to C₁₂ alkyl side chains, calcium nonylphenol sulfide, oil solublephenates and sulfurized phenates, phosphosulfurized or sulfurizedhydrocarbons or esters, phosphorous esters, metal thiocarbamates, oilsoluble copper compounds as described in, for example, U.S. Pat. No.4,867,890.

Different types of zinc dialkyldithiophosphates or zincdiaryldithiophosphates are available depending on the alcohol or phenolused in their manufacture, and the hydrocarbyl group present stronglyinfluences their activity: the greater the thermal stability of theproduct, the lower the antioxidant activity. But as stated above, therehas been a move away from using this type of antioxidants at least inturbine oils because they are sensitive to moisture and the hydrolysisproducts and can precipitate in the presence of water. Another type ofcommon antioxidants is 2,6-ditertiarybutyl p-cresol (also known as DBPCor BHT), but because of its high volatility and solid form, it isincluded in only a limited number of additive packages.

Higher molecular weight products, such as aromatic amines and hinderedphenols, have been introduced to replace the BHT, with the formergenerally being more active than the latter. In particular, thealkylated derivatives of aromatic amines are known to be effective athigh temperatures. Typical oil soluble aromatic amines having at leasttwo aromatic groups attached directly to one amine nitrogen contain from6 to 16 carbon atoms. The amines may contain more than two aromaticgroups. The aromatic rings are often substituted by one or moresubstituents selected from, for example, alkyl, cycloalkyl, alkoxy,aryloxy, acyl, acylamino, hydroxy, and nitro groups. In addition totheir capacity to reduce fluid viscosity and acidity, which are the twomost common indicators of oxidation, they are able to control depositformation on hot surfaces, thus reducing the risk of an engine failureas a result of deposits. Aromatic amines are sometimes used withphenothaizine derivatives (e.g., a sulfur-containing antioxidant) inaviation turbine oils. Certain amines or synergistic mixtures of aminesand phenols are known to be highly cost effective antioxidants, butlarge amounts of these materials are known to form deposits duringoxidation and color the finished lubricant. These mixtures are thustypically used in small amounts if they are included in an additivepackage.

Rust and Corrosion Inhibitors Rust is a continuing problem in turbineswhere carbon steel is present because water contamination can bedifficult to avoid, especially in steam turbines and hydraulic turbines.Acid is also almost always present in degraded oils and can attackmetals. In order to avoid rusting and corrosion, certain chemicals havebeen found to protect the metal surfaces. For steel, for example, suchinhibitors are usually highly polar materials such as organic acids,esters or amides, which form an adsorbed film on the surface of themetal that physically hinders the transfer of water to the surface.Because of this mode of action, careful formulation is called for toavoid interaction with other surface-active materials such as antiwearadditives, and to minimize the impact on foaming/air release properties.Moreover, some if not most of the industrial turbines operate in salineenvironments. Rust protection is often necessary against salt water,which is a substantially more severe requirement than the mereprotection against distilled water.

In addition to steel, other metals are susceptible to attack fromdegraded oils or other additives, such as sulfur-containingantiwear/extreme-pressure additives. Of these other metals, copper isthe most important, not only because of its common use in constructingindustrial turbines but also because it may catalyze the breakdown ofoils and fluids when present in soluble salt forms at very lowconcentrations. This can result in the formation of sulfide-containingdeposits. Certain chemicals called “metal passivators” are known toprevent this type of copper corrosion. Metal passivators are typicallyof the triazole family.

Rust inhibitor or anticorrosion agents may be a nonionic polyoxyethylenesurface active agent. Nonionic polyoxyethylene surface active agentsinclude, but are not limited to, polyoxyethylene lauryl ether,polyoxyethylene higher alcohol ether, polyoxyethylene nonylphenyl ether,polyoxyethylene octylphenyl ether, polyoxyethylene octyl stearyl ether,polyoxyethylene oleyl ether, polyoxyethylene sorbitol monostearate,polyoxyethylene sorbitol mono-oleate, and polyethylene glycolmonooleate. Rust inhibitors or anticorrosion agents may also be othercompounds, which include, for example, stearic acid and other fattyacids, dicarboxylic acids, metal soaps, fatty acid amine salts, metalsalts of heavy sulfonic acid, partial carboxylic acid ester ofpolyhydric alcohols, and phosphoric esters.

Antifoamants The inhibition of foaming is of particular importance whenlubricating industrial turbines, especially in hydraulic turbineswherein the turbine oils not only serve to lubricate the system and butalso to transmit power in the presence of a great deal of water. It isalso known that the stability of foam increases when more additives areadded to an oil. Although turbine oils are typically not heavilyadditized for this very reason, a small amount of one or moreantifoamants is typically included in turbine additive packages. Variousknown foam inhibitors can service this purpose, including, for example,dimethylsiloxane polymers, alkylmethacrylate copolymers, alkylacrylatecopolymers and others. Typically these compounds have borderlinesolubility in lubricating oils, and function by reducing the surfacetension at the interface of the air bubble, thus allowing the bubble toburst more easily. To function effectively they are usually present atvery low levels, such as at or below about 30 ppm, or about 25 ppm, orabout 20 ppm, or even about 10 ppm, because at higher levels thesolubility becomes an issue, manifested by an increase in the cloudinessof the lubricant, and in more extreme cases, by the formation offloating debris or precipitation. The effectiveness of an antifoamantcan be determined according to the ASTM D892-06, which uses air flowingthrough a porous ball to create foam in the test oil sample. The amountof foam and its stability are measured at 24° C. and 94° C. A variationof this test, ASTM D6082-06, can also be used to measure foaming at 150°C.

Detergents/Dispersants Compared to other industrial oils, turbine oilstend not to be heavily additized with detergents or dispersants becauseof the need to allow solid particles to settle rather than suspend sothat they may be removed through sump drain or kidney loop filtrationsystems that are typically present in industrial turbines. This howeverdoes not mean that the turbine oil cannot comprise metal-containingdetergents or ashless dispersants. If present, the amount of detergentsand/or dispersants in the turbine oil should be sufficiently low so thatthe capacity of the oil to settle solid particles and/or contaminantsand other properties of the oil is not negatively affected.Metal-containing or ash-forming detergents function both as detergentsto reduce or remove deposits and as acid neutralizers or rustinhibitors, thereby reducing wear and corrosion and extending enginelife. Detergents generally comprise a polar head with long hydrophobictail, with the polar head comprising a metal salt, and especially anoverbased salt, of an acid organic compound. Overbased salts, oroverbased materials, are single phase, homogeneous Newtonian systemscharacterized by a metal content in excess of that which would bepresent according to the stoichiometry of the metal and the particularacidic organic compound reacted with the metal. The overbased materialsare prepared by reacting an acidic material (typically an inorganic acidor lower carboxylic acid, preferably carbon dioxide) with a mixturecomprising an acidic organic compound, in a reaction medium comprisingat least one inert, organic solvent (such as mineral oil, naphtha,toluene, xylene) in the presence of a stoichiometric excess of a metalbase and a promoter. Methods of preparing various detergents, such asthe carboxylates, the phenates, and the sulfonates, are known in theart. Suitable detergents may also be sulfurized, the processes of whichare known also to those skilled in the art. Since steam turbine oils arelikely to interact with water, having good water separability isdesirable. In some embodiments, excess usage detergents may destroywater separability, thus water separability property should be balancedwith the desirable properties obtained with the use of dispersant anddetergents.

Other Additives Other additives may be incorporated into thecompositions to satisfy particular performance requirements. Examples ofsuch other additives include, for example, seal fixes or seal pacifiers,VI improvers, friction modifiers. Detergents/dispersants are rarely ifever employed in turbine oils, and even when employed, the amounts ofsuch additives are kept sufficiently low so that the capacity of the oilto settle solid particles and/or contaminants and other properties ofthe oils, such as water separability, are not negatively affected.

In one embodiment, standard turbine oil additive packages may alsocomprise antiwear/extreme pressure additives and demulsifiers.Dihydrocarbyl dithiophosphate metal salts are frequently used asantiwear and antioxidant agents. The metal may be an alkali or alkalineearth metal, or aluminum, lead, tin, molybdenum, manganese, nickel orcopper. The zinc salts are the most commonly used in non-turbinelubricating oil. In turbine oils, however, this amount of such salts maybe substantially reduced because of their tendency to hydrolyze whenexposed to moisture, and the hydrolysis products (e.g., zinc oxide andhydroxide) can precipitate.

These salts may be prepared in accordance with known techniques by firstforming a dihydrocarbyl dithiophosphoric acid (DDPA), usually byreaction of one or more alcohol or a phenol with P₂S₅, and thenneutralizing the formed DDPA with a zinc compound. Specifically,oil-soluble zinc dialkyldithiophosphates may be produced fromdialkykyldithiophosphoric acids of the formula:

The hydroxyl alkyl compounds from which the dialkyldithiophosphoricacids are derived can be represented generically by the formula ROH orR′OH, wherein R or R′ is alkyl or substituted alkyl, preferably branchedor non-branched alkyl containing 3 to 30 carbon atoms. More preferably,R or R′ is a branched or non-branched alkyl containing 3 to 8 carbonatoms. Mixtures of hydroxyl alkyl compounds may also be used. Thesehydroxyl alkyl compounds need not be monohydroxy alkyl compounds. Thedialkyldithiophosphoric acids may thus be prepared from mono-, di-,tri-, tetra-, and other polyhydroxy alkyl compounds, or mixtures of twoor more of the foregoing. The phosphorus pentasulfide reactant used inthe dialkyldithiophosphoric acid formation step may contain minoramounts of any one or more of P₂S₃, P₄S₃, P₄S₇, or P₄S₉. Compositions assuch may also contain minor amounts of free sulfur.

A small amount of one or more VI improvers may also be included in theadditive packages. Generally, polymeric materials useful as VI improversare those having number average molecular weights (Mn) of from about5,000 to about 250,000, preferably from about 15,000 to about 200,000,more preferably from about 20,000 to 150,000 Daltons. The oiltemperature controls coiling of the polymer molecules, which in turncontrols the degree to which the polymers increase viscosity. The higherthe temperature, the less the coiling and the greater the “thickening”effect of the polymer. Thus, as temperature increases, there is lessthinning of the lubricant compared to VI improver-containing oils. TheseVI improvers can optionally be grafted with grafting materials such as,for example, maleic anhydride, and the grafted material can be reactedwith, for example, amines, amides, nitrogen-containing heterocycliccompounds or alcohol, to form multifunctional viscosity improvers(dispersant-viscosity modifiers).

Because of the high costs of known viscosity index improvers, andbecause of their sensitivity to high temperature or otherwise harshconditions, the amount of these materials that may be included in aturbine oil is heavily limited. For example, the amount of the viscosityindex modifiers in the turbine oils may be below about 5 wt. %, or belowabout 3 wt. %, or below about 1 wt. %, or even below about 0.1 wt. %,based on the total weight of the finished turbine oil.

The additive packages may further comprise a sulfur-containingmolybdenum compound. Certain sulfur-containing organo-molybdenumcompounds are known to function as friction modifiers in lubricating oilcompositions, while also providing antioxidant and antiwear credits to alubricating oil composition. Examples of such oil solubleorgano-molybdenum compounds include dithiocarbamates, dithiophosphates,dithiophosphinates, xanthates, thioxanthates, sulfides, and the like,and mixtures thereof. Methods of preparing these compounds are known inthe art.

Seal fixes are also termed seal swelling agents or seal pacifiers. Theyare often employed in lubricant or additive compositions to insureproper elastomer sealing, and prevent premature seal failures andleakages. Seal swell agents may be, for example, oil-soluble, saturated,aliphatic, or aromatic hydrocarbon esters such asdi-2-ethylhexylphthalate, mineral oils with aliphatic alcohols such astridecyl alcohol, triphosphite ester in combination with ahydrocarbonyl-substituted phenol, and di-2-ethylhexylsebacate.

Some of the above-mentioned additives can provide a multiplicity ofeffects; thus for example, a single additive may act as a dispersant aswell as an oxidation inhibitor. These multifunctional additives are wellknown.

Various turbine additive packages are known and/or commerciallyavailable. Those include, for example, certain of the HITEC™ additivepackages manufactured by AFTON®.

Properties To monitor the in-service turbine oils and to warn ofsubstantial losses in oxidation resistance, a standard rotating pressurevessel oxidation test, RPVOT or ASTM D 2272-02, has been developed. Forexample, a RPVOT decrease or “drop” of 75% (or a 25% retention) from thenew oil RPVOT value with a concurrent increase in acid number (AN) hasbeen used as a warning limit for loss of oxidative stability. A100-minute limit for a 75% reduction in RPVOT value is often used as analternative indicator of loss of that stability in a Group I finishedturbine oil. In one embodiment, the turbine oil composition has an RPVOTvalue of at least 1500 minutes. In a second embodiment, RPVOT value ofat least 1700 minutes. In a third embodiment, an RPVOT value of at least1900 minutes. In a fourth embodiment, an RPVOT value of at least 2000minutes. In a fifth embodiment, at least 2500 minutes.

In all turbines, and especially in turbines with small sumps and minimalresidence time, entrained air mixtures could be sent to bearings andcritical hydraulic control elements, causing failure in lubricant filmstrength, loss of system control, and increased rate of oxidation.Accordingly, most steam and gas turbine OEMs specify air-release speedlimits in their oil specification requirements, which can range from aslow as 4 minutes (defined as the time for the air entrained in the oilduring the test procedure to detrain to 0.2% by volume). Persons skilledin the art may use standard test method ASTM D3427-06 to measure thetime it takes to release air from a formulated turbine oil. The turbineoil composition comprising a major amount of one or more FTBOs hasimproved capacity to release entrained air as compared to acorresponding turbine oil formulated with the same additives but withonly non-FTBOs.

In one embodiment, the turbine oil composition also has a reducedtendency to catch fire as compared to a corresponding turbine oilcomposition comprising the same additive but only non-FTBOs. A standardtest, ASTM D92-05a, can be used to measure the flash point of a finishedturbine oil. In one embodiment, the composition has an improved flashpoint, typically above about 236° C., or above about 238° C., or aboveabout 240° C., or above about 245° C., or even above about 250° C., thusrendering a relatively low tendency to catch fire under hightemperatures. Another standard test, ASTM E659-78 (Rev. 2005), can beused to measure the autoignition temperature of a finished turbine oil,which is another indicator of the volatility of the oil. In oneembodiment, the turbine composition has an autoignition temperature ofgreater than about 360° C. In a second embodiment, greater than about362° C. In a third embodiment, greater than about 365° C. In a fourthembodiment, greater than about 370° C.

In one embodiment, the turbine oil composition further has improvedwater separability, a characteristic that is especially desirable whenthe industrial turbine housing the composition is operated in thepresence of water. A standard test method, ASTM D1401-02 can be used todemonstrate this improvement in water separability. In this test 40 mLof oil is mixed with 40 ml of water at 54° C. and the time taken for theresulting emulsion to reduce to 3 mL or less (considered to be completeseparation) is recorded. If complete separation does not occur, then thevolume of oil, water and emulsion present is recorded. In oneembodiment, the turbine oil composition separates from water in lessthan 30 minutes as measured according to ASTM D-1401-2002. In a secondembodiment, the composition separates from water in less than 15minutes. In a third embodiment, less than 10 minutes.

In one embodiment, the turbine oil composition also has a reducedtendency to form sludge and/or varnish. A standard test method, ASTMD4310-06b, can be used to demonstrate this improvement by measuring theamount of sludge formed during a specified time period and comparing itwith the amount obtained from a corresponding turbine oil comprisingonly non-FTBOs.

It should be further noted that the turbine oil composition meets atleast one of DIN 51515-1 and DIN 51515-2 specifications for turbineoils. In a second embodiment, the turbine composition further meetsmajor industry specifications for gas and turbine oils, including thoseof GE, Alstom, Mitsubishi Heavy Industries and Siemens. This inventionwill be further understood by reference to the following examples.

EXAMPLES The following examples are provided to illustrate the presentinvention without limiting it. While the present invention has beendescribed with reference to specific embodiments, this application isintended to encompass those various changes and substitutions that maybe made by those skilled in the art without departing from the scope ofthe appended claims.

The Fischer-Tropsch derived base oils (FTBOs) used in some of theexamples were produced by hydroisomerization dewaxing a 50/50 mix ofLuxco 160 petroleum-based wax and Moore & Munger C80 Fe-based FT wax.The hydroisomerized product was hydrofinished and fractionated by vacuumdistillation. The distillate fractions were selected having theproperties described in Table 4. FTBO A is an example of a base oil madefrom a waxy feed having a VI greater than an amount defined by theequation: VI=28×Ln(Kinematic Viscosity at 100° C.)+105. It also has avery low traction coefficient.

1. Performance Comparison: Base Oils in Turbine Oil Compositions

Each of Base Oil Mixtures A to E was prepared by blending two basestocks in accordance with Table 1. Specifically, Base Oil Mixture A wasprepared by blending two API group I base stocks of different viscosity,Base Oil Mixture B was prepared by blending two API Group II base stocksof different viscosity, Base Oil Mixture C was prepared by blending twoAPI Group III base stocks of different viscosity, Base Oil Mixture D wasprepared by blending two PAO base stocks of different viscosity, andBase Oil Mixture E was prepared by blending the two FTBOs of differentviscosity described above, so that the final viscosity of each Base OilMixture was about 30.4 mm²/s. at 40° C. These Base Oil Mixtures werefurther blended with six different turbine additive packages, includinga commercially available rust and oxidation inhibited additive packagefor turbine oils (“AD Package”) and five different additive packages(“PAPs”), i.e., PAP1 to PAP5, so that the finished oils, i.e., A1 to A6,B1 to B6, C1 to C6, D1 to D6, and E1 to E6, comprised greater than about95 wt. % of a Base Oil Mixture and less than about 5 wt. % of anadditive package.

A standard method, ASTM D2270-04, was used to measure the VIs of thesefinished oils.

These finished oils were also tested for oxidative stability in astandard Rotating Pressure Vessel Oxidation Test (RPVOT) or ASTMD2272-02. In that test, an oil sample, water and a copper catalyst coilwere placed in a pressurized vessel. The vessel was then charged withoxygen, placed in a temperature-controlled bath and rotated. The time ittook to reach a decrease in pressure of 25 psi in the vessel wasreported. Improvements in performance can be correlated with increasesin the reported time.

These finished oils were further evaluated for evaporation weight lossin a standard bench test ASTM D972-02. In that test, a weighed oilsample was placed in an evaporation cell in an oil bath at the desiredtest temperature of 149° C. Heated air at a specified flow rate was thenpassed over the sample surface for 22 hours, after which the loss insample mass was determined. Improvements in performance can becorrelated with decreases in the evaporation weight loss.

Moreover, the flash points of these finished oils were determined usinga standard bench test, the Cleveland Open Cup ASTM D92-05a. In thattest, the oil samples were placed in test cups individually. Amechanical swinging arm then moved a small test flame across the top ofeach cup. The temperatures at which the test oils caught fire werereported. Improvements in performance, i.e., reductions in the tendencyto catch fire, can be correlated with increases in the flash pointtemperature. In conjunction, the autoignition temperatures of these oilswere measured using a standard method, ASTM E 659 (Rev. 2005). In thattest, a sample oil was injected into a test beaker or container filledwith heated air. The temperature of the air at which the oil samplespontaneously ignited was reported as the autoignition temperature.Improvements in performance, i.e., reductions in the tendency to catchfire, can be correlated with increases in the autoignition temperature.

Furthermore, the water separability of each of these finished oils wasdetermined using a standard test, ASTM D1401-02. In that test, a sampleoil was stirred at 40° C. with an equal volume (40 ml) of water, and thetime it took to separate the resulting emulsion (if formed) wasreported. Improvements in performance can be correlated with decreasesin the time it takes to separate the water phases from the oil phases.

Their capacities to release entrained air were further compared usingASTM D3427-06. In that test, individual test oil was saturated with airbubbles at about 50° C., and the time (minutes) it took for the fluid toreturn to an air content of 0.2% was reported. Improvements inperformance can be correlated with decreases in the reported time. TABLE1 Comparison of Performance Characteristics in Bench Tests Base D2272D92 E659 D1401 D3427 # Oil Mix Additive VI (min) (° C.) D972 (° C.)O/W/E/T(min) (min) A1 Gp. I AD Package 92 702 204 10.72 374 40/40/0/151.33 A2 PAP 1 92 952.7 210 10.95 332 40/40/0/25 1.8 A3 PAP 2 91 1023 21710.97 358 40/40/0/15 1.42 A4 PAP 3 93 320 — 10.46 — 40/40/0/15 — A5 PAP4 99 252 — — 351 41/39/0/5 4.6 A6 PAP 5 91 454 — 9.87 — 40/40/0/14 — B1Gp. II R&O 97 1229 206 7.87 368 40/40/0/15 0.9 B2 PAP 1 98 1912 20810.28 338 40/40/0/15 1.25 B3 PAP 2 96 1596 215 7.99 358 40/40/0/10 0.92B4 PAP 3 105 476 — 7.59 — 40/40/0/15 — B5 PAP 4 95 287 — — 34240/40/0/5.5 3.43 B6 PAP 5 96 1468 — 7.72 — 40/40/0/13 — C Gp. III ADPackage 135 1738 232 2.61 369 40/40/0/15 0.8 C PAP 1 127 1824 232 2.95380 40/40/0/15 1.1 C PAP 2 125 2859 242 2.68 363 40/40/0/10 0.68 C PAP 3126 638 — 3.21 — 40/40/0/14 — C PAP 4 125 371 — — 338 40/40/0/7 1.02 CPAP 5 125 2572 — 2.54 — 40/40/0/11 — D PAO AD Package 129 1935 236 1.53366 40/40/0/15 <0.17 D PAP 1 128 1834 236 1.46 363 40/40/0/15 <0.17 DPAP 2 127 3124 240 1.36 375 40/40/0/10 0.43 D PAP 3 127 698 — 1.99 —40/40/0/12 — D PAP 4 127 431 — — 343 40/40/0/7 <0.50 D PAP 5 127 2058 —1.38 — 40/40/0/11.5 — E1 FTBO AD Package 160 1965 240 2.12 37040/40/0/10 1 E2 PAP 1 152 1991 252 1.84 362 40/40/0/10 0.4 E3 PAP 2 1503480 241 5.61 360 40/40/0/10 0.6 E4 PAP 3 150 661 — 2.65 — 40/40/0/6 —E5 PAP 4 151 438 — — 370 40/40/0/6 0.9 E6 PAP 5 151 2811 — 1.61 —40/40/0/10 —2. Other Indications of Improvements Conferred by Turbine OilsComprising FTBOs

The improvements in oxidative stability, thermal stability, and sludgeforming tendencies were further verified with a second set of turbineoil compositions, which are prepared in accordance with Table 2. Each ofthe base oil mixtures F to J were prepared by blending two base stocksof different viscosity so that the final viscosity in each base oilmixture was again about 30.4 mm²/s at 40° C. These base oil mixtureswere subsequently blended with the same set of turbine additives, acommercially available rust and oxidation inhibited additive package forturbine oils (“AD Package”), and PAP1 to PAP5, forming finished turbineoil samples F1 to F6, G1 to G6, H1 to H5, I1 to I6 and J1 to J6.

The VIs and RPVOT oxidative stabilities of these oils were measuredusing standard methods ASTM D2270-04 and ASTM D2272-02, respectively.The thermal stability of each was tested using the Cincinnati MachineThermal Stability Test A. In that test, steel and copper rods wereplaced in the sample oils for 168 hours at 135° C., and the viscositychange and sludge levels were reported. Improvements in thermalstability can be correlated with decreases in either or both the amountof sludge and/or the % viscosity change at either 40 or 100° C.

A Ramsbottom Carbon Residue test, ASTM D524-04, was used to evaluate theoils' tendencies to form carbon residues. In that test, each of the oilsamples, after being weighed into a special glass bulb, was placed in ametal furnace, heated to 550° C. quickly and maintained at thattemperature for 20 minutes, evaporating all volatile materials. Afterthe test, the bulb was cooled and weighed, and the residues remainingwas reported in wt. % of the original sample. Improvements inperformance can be correlated with decreases in the wt. % of theresidues. TABLE 2 Results of Cincinnati Machine Thermal Test A,Ramsbottom carbon ASTM D524-04, and Modified RPVOT Sludge Test. CMThermal A Base Sludge % vis. change D524 % # Oil Mix Add. VI (mg/100 ml)@40/100° C. residue F1 Gp. I AD — — — — Package F2 PAP1 — — — — F3 PAP2102 28.9 3.2 0.08 F4 PAP3 100 22.9 3.5 0.07 F5 PAP4 101 24.4 4.6 0.07 F6PAP5 103 40.3 3.9 0.05 G1 Gp. II AD 108 6.55 2 0.04 Package G2 PAP1 1079.4 1.7 0.03 G3 PAP2 107 19.7 1.4 0.06 G4 PAP3 107 6.65 1 0.04 G5 PAP4106 11.4 1.3 0.04 G6 PAP5 108 8.6 1.3 0.03 H1 Gp. III AD 131 4.65 6.30.03 Package H2 PAP1 131 12.4 3.6 0.03 H3 PAP2 135 14.75 0.7 0.06 H4PAP3 135 7.65 0.7 0.03 H5 PAP4 135 7.4 1.0 0.04 H6 PAP5 136 5.8 0.3 0.03I1 PAO AD 137 5.95 1.7 0.02 Package I2 PAP1 137 7.8 0.3 0.03 I3 PAP2 13611.25 0.3 0.05 I4 PAP3 137 5.9 0 0.03 I5 PAP4 137 11.6 1.0 0.04 I6 PAP5137 6.7 −3.5 0.02 J1 FTBO AD 162 5.45 2.7 0.02 Package J2 PAP1 162 5.32.3 0.02 J3 PAP2 152 9.65 0.7 0.05 J4 PAP3 151 5.9 1 0.03 J5 PAP4 1557.0 2.0 0.04 J6 PAP5 153 6.55 0 0.023. Comparisons of Performance Characteristics of Turbine Oils InCompressor Tests

Five additional turbine oil compositions were prepared, each comprisingbase oils from a different source but the same commercially availablerust and oxidation inhibited additive package for turbine oils (“ADPackage”). These compositions were prepared in accordance with Table 3.

A standard test, ASTM D2270-04, was used to determine the VI of each ofthese oils. The RPVOT as described Example 1 above was used to determinethe time it took to reach a drop in pressure of 25 psi as the result ofoxidation.

To evaluate the sample oils in their capacities to deactivate copper andiron elements and prevent oxidation catalyzed by those metals, a CIGREtest was also employed. In that test, oxygen was passed through a glasstube filled with 40 grams of a sample oil at 120° C. and at a flow rateof 1 liter per hour. Each test was conducted for 168 hours, and theamount oxidation products trapped in the water phase were measured andreported as volatile acidity. Improvements in oxidative stability can becorrelated with decreases in total sludge, soluble acidity, the amountof total oxidation product or increases in the ratio of sludge on top.

Moreover, compressor tests ROCOT and PNEUROP were used to furtherdemonstrate the improvements in performance imparted by the FTBOs.Specifically, the PNEUROP test was conducted using 40 grams of each oilsample in the absence of catalysts, in a vessel heated to 200° C. andwith air flowing through at a speed of 15 liters per hour for 12 hours.The amount of evaporated oil as well as the amount of carbon formationwere reported. Improvements can be correlated with either decreases inevaporation loss or decreases in the amount of carbon formation. TheROCOT test, on the other hand, was conducted using 40 grams of each oilsample in the presence of an iron naphthenate catalyst, in a vesselheated to 140° C. and with air flowing through at a speed of 15 litersper hour for 168 hours. The amount of evaporation loss, viscosityincrease, TAN increase and sludge formation were reported. Improvementsin performance can be correlated with one or more of the following: (1)decreases in evaporation loss; (2) reductions in the extent of change inkinematic viscosity; (3) reductions in the amount of TAN; (4) reductionsin sludge formation.

Furthermore, a standard sludge test, ASTM D4310-06b, was used to comparethe turbine oil composition comprising a major amount of FTBO with aturbine oil composition comprising the same amount of Group III base oiland a turbine oil composition comprising the same amount of Group I baseoil. Improvements in performance can be correlated with decreases in theamount of sludge formed during the test. TABLE 3 CIGRE and CompressorTests: Gp I + AD Gp II + AD Gp III + AD PAO + AD FTBO + AD PropertiesPackage Package Package Package Package VI 103 — 127 138 162 RPVOT (min)579.4 1124 1322 1242 1620 CIGRE Volatility acidity 0.055 0.10 0.0250.075 0.06 Total Sludge 0.11 0.05 0.045 0.07 0.055 Soluble acidity 0.410.335 0.86 0.16 0.175 Total Oxidation Product 0.26 0.19 0.325 0.14 0.125Ratio of Sludge on Top 0.265 0.265 0.185 0.495 0.44 PNEUROP Evaporationloss 4.14 10.76 7.185 3.96 8.82 CCT 0.172 0.950 0.662 0.119 0.321 ROCOTEvaporation Loss % 3.88 4.5 1.34 1.36 1.58 Kin. Vis. Increase % 8.88 5.51.91 2.15 3.8 TAN increase mg 0.12 0.09 0.085 0.09 0.08 KOH/g 0.14 0.0280.045 0.06 0.065 Heptane sludge % Sludge ASTM D4310-06b 215.5 — 88.5 —170 Amount of sludge, mg

TABLE 4 FTBO Properties FTBO A FTBO B Viscosity at 100° C., cSt 7.5974.45 Viscosity Index 162 146 Pour Point, ° C. −13 −18 Total Wt %Aromatics 0.0168 0.0129 Wt % Olefins 0.0 0.0 FIMS, Wt % Alkanes 58.365.2 1-Unsaturations 34.4 27.5 2- to 6- Unsaturations 7.3 7.3 Total100.0 100.0 Total wt % Molecules with Cycloparaffinic 41.7 34.8Functionality Ratio of Monocycloparaffins to 4.7 3.8 MulticycloparaffinsOxidator BN, hours 45.42 44.09 X in the equation: VI = 28 × 105.2 104.1Ln(VIS100) + X Traction Coefficient at 15 cSt <0.021 0.0235 NoackVolatility, wt % 3.92 8.52 N-d-M Carbon Types, wt % Paraffinic Carbon92.46 93.97 Naphthenic Carbon 7.54 6.03 Aromatic Carbon 0.00 8.52

For the purposes of this specification and appended claims, unlessotherwise indicated, all numbers expressing quantities, percentages orproportions, and other numerical values used in the specification andclaims, are to be understood as being modified in all instances by theterm “about.” Accordingly, unless indicated to the contrary, thenumerical parameters set forth in the following specification andattached claims are approximations that may vary depending upon thedesired properties sought to be obtained and/or the precision of aninstrument for measuring the value. Furthermore, all ranges disclosedherein are inclusive of the endpoints and are independently combinable.In general, unless otherwise indicated, singular elements may be in theplural and vice versa with no loss of generality. As used herein, theterm “include” and its grammatical variants are intended to benon-limiting, such that recitation of items in a list is not to theexclusion of other like items that can be substituted or added to thelisted items.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to make and use the invention. The patentable scope is defined bythe claims, and may include other examples that occur to those skilledin the art. Such other examples are intended to be within the scope ofthe claims if they have structural elements that do not differ from theliteral language of the claims, or if they include equivalent structuralelements with insubstantial differences from the literal languages ofthe claims. All citations referred herein are expressly incorporatedherein by reference.

1. A turbine oil composition comprising an admixture of: (a) a major amount of at least an isomerized base oil having consecutive numbers of carbon atoms and has less than 25 wt % naphthenic carbon by n-d-M; and (b) a minor amount of one or more standard turbine oil additive packages; wherein the turbine oil composition has a viscosity index of greater than about
 150. 2. The composition of claim 1, wherein isomerized base oil has consecutive numbers of carbon atoms and has less than 10 wt % naphthenic carbon by n-d-M.
 3. The composition of claim 1, wherein isomerized base oil is a Fischer-Tropsch derived base oil made from a waxy feed.
 4. The composition of claim 1, wherein isomerized base oil has an average molecular weight between 600 and 1100, and an average degree of branching in the molecules between 6.5 and 10 alkyl branches per 100 carbon atoms.
 5. The composition of claim 1, wherein the isomerized base oil has a wt % Noack volatility between 0 and
 100. 6. The composition of claim 1, wherein the isomerized base oil has a ratio of weight percent molecules with monocycloparaffinic functionality to weight percent molecules with multicycloparaffinic functionality of greater than
 15. 7. The composition of claim 1, wherein the isomerized base oil is made from a process in which the highly paraffinic wax is hydroisomerized using a shape selective intermediate pore size molecular sieve comprising a noble metal hydrogenation component, and under conditions of about 600° F. to 750° F. and wherein the isomerized base oil has a Noack volatility of less than 50 weight %.
 8. The composition of claim 1, wherein the at least an isomerized base oil is greater than about 60 wt. %, based on the total weight of the turbine oil composition.
 9. The composition of claim 8, wherein the at least an isomerized base oil is greater than about 80 wt. %, based on the total weight of the turbine oil composition.
 10. The composition of claim 9, wherein the at least an isomerized base oil is greater than about 90 wt. %, based on the total weight of the turbine oil composition.
 11. The composition of claim 10, wherein the at least an isomerized base oil is greater than about 90 wt. %, based on the total weight of the turbine oil composition.
 12. The composition of claim 1 having a viscosity index of greater than about
 153. 13. The composition of claim 12, having a viscosity index of greater than about
 160. 14. The composition of claim 1, having a flash point of greater than about 236° C., as measured using ASTM D92.
 15. The composition of claim 14, having a flash point of greater than about 245° C., as measured using ASTM D92.
 16. The composition of claim 1, having an autoignition temperature of greater than about 360° C., as measured using ASTM E 659 (Rev. 2005).
 17. The composition of claim 16, having an autoignition temperature of greater than about 370° C., as measured using ASTM E 659 (Rev. 2005).
 18. The composition of claim 1, wherein the one or more standard turbine oil additive packages comprise one or more materials selected from: antioxidants, wear inhibitors, demulsifiers, antifoamants, and rust/corrosion inhibitors.
 19. The composition of claim 20, wherein the one or more standard turbine oil additive packages further comprise one or more materials selected from: detergents, ashless dispersants, viscosity index improvers, friction modifiers, seal fixes, and multifunctional additives.
 20. The composition of claim 1, wherein the at least an isomerized base oil has a viscosity index of no less than about
 140. 21. The composition of claim 1, wherein the at least an isomerized base oil has a kinematic viscosity of greater than about 2 mm²/s at 100° C.
 22. The composition of claim 1, wherein the at least an isomerized base oil has a pour point of below about −8° C.
 23. The composition of claim 1, wherein the at least an isomerized base oil has a cloud point of below about 5° C.
 24. The composition of claim 1, wherein the at least an isomerized base oil has an Oxidator BN of greater than about 40 hours.
 25. A method of improving the performance and service life of an industrial turbine, said method comprising operating the turbine in the presence of a turbine oil composition comprising an admixture of: a major amount of at least an isomerized base oil having consecutive numbers of carbon atoms and has less than 25 wt % naphthenic carbon by n-d-M; and a minor amount of one or more standard turbine oil additive packages; wherein the turbine oil composition has a viscosity index of greater than about
 150. 